T1-201 myocardial perfusion scintigraphy has been widely utilized for non- invasive evaluation of coronary artery disease (CAD). Extensive research and development by our group and others has resulted in the development of objective methods for analysis of images and single photon emission computerized tomography (SPECT). Nevertheless, quantitative Tl-201 SPECT has not yet reached its full potential because of suboptimal physical characteristics of the Tl-201 agent. Recently, Technetium-99m labeled Methoxy Isobutyl Isonitrile (Tc-MIBI) has been developed which obviates most of the unfavorable characteristics of Tl-201. The overall objective of this proposal is to develop, validate and assess clinical applications of a noninvasive method for quantitative assessment of myocardial perfusion using Tc-MIBI SPECT. This overall objective is addressed in two separate sections. I. Relative Quantitation of Myocardial Perfusion: The long term objective of this section is to develop, optimize and validate methods for acquisition, filtering, reconstruction, quantitative analysis, and displaying Tc-MIBI SPECT data. The hypothesis to be tested is whether relative quantitation (determination of the volume of abnormally perfused myocardium) of Tc-MIBI Spect data can be implemented in patient studies in a manner in which they will more accurately predict quantitative coronary angiographic findings and the presence and size of perfusion defects. II. Absolute Quantitation of Myocardial Perfusion: The long-term objective of this section is to develop methods to obtain, in the clinical setting, a linear relation between pixel count values and myocardial tracer concentrations and thus obtain truly quantitative imaging. This should result in improved uniformity of normal tissue count distribution, increased lesion contrast and measurement of actual myocardial blood flow. On order to fulfill this objective it is necessary to apply corrections for: Compton Scatter, attenuation and object size of the myocardium due to finite resolution effects.